A disposable rubber glove used widely in daily life, including housework, food industry, electronic industry and medical field, is made by dip molding of natural rubber or carboxylic acid-modified nitrile-based copolymer latex. Recently, carboxylic acid-modified nitrile-based gloves have been spotlighted in the market of disposable gloves due to the problems of allergy caused by natural protein of natural rubber and unstable supply and demand.
Such carboxylic acid-modified nitrile-based gloves are made by dipping a mold coated with a solidifier into latex formed by emulsion latex. A large amount of emulsifier is used for emulsion polymerization, and such emulsifier becomes a cause substance for foaming and pinhole formation during the production of gloves.
During the production of gloves, pinholes may form a puncture in gloves, leading to production of defected gloves. Thus, for the purpose of defoaming, a defoaming agent is introduced or a maturation process is required. Introducing a defoaming agent may cause defects in gloves since the defoaming agent itself may function as a foreign material. In addition, maturation undesirably increases the processing time.
Further, when an emulsifier is not removed sufficiently during leaching of the manufacturing process, it may remain in gloves and cause foaming or slipping upon the contact with water after the users put on the gloves. Such emulsifier remaining in gloves is one of the chemicals remaining in gloves like calcium and a releasing agent, and is known to adversely affect the quality of gloves.
Therefore, it is required to develop stable latex including an emulsifier that does not cause defects in dip molding products resulting from generation of a large amount of foam during polymerization or degradation of a feel of use resulting from outflow on the surface of dip molding products. To solve such problems, many studies have been conducted.
Hence, the present inventors have conducted researches about stable latex that does not generate a large amount of foam during polymerization or does not degrade a feel of use resulting from outflow on the surface of dip molding products. As a result, the inventors have found that when preparing latex by adding a reactive emulsifier different from the conventional adsorption/desorption type emulsifier, it is possible to obtain stable latex by using a small amount of reactive emulsifier while not generating a large amount of foam. The present invention is based on this finding.